In general, gas dehydrating systems are designed to remove water vapor from a natural gas stream. Such systems typically comprise a separator that receives liquids from water vapor laden gas, an absorber (or contactor) for removing water vapor from the wet gas, and a pump (e.g., glycol pump) for circulating a dehydrating agent (e.g., glycol) within the system. The glycol is generally supplied to the absorber in a “dry” low water vapor pressure condition and is removed from the absorber in a “wet” high water vapor pressure condition (i.e., “rich glycol”). This wet glycol is then continuously-removed from the absorber and circulated through a reboiler for removing the absorbed water from the glycol. By removing water vapor from the wet gas, dry gas suitable for commercial usage is created.
The pressure created from gas streams and natural gas wells is highly variable, and given that gas operated pumps often require large amounts of energy, changes in gas pressures during day-to-day operation might cause conventional glycol pumps to stall. As a result, the stalling of the glycol pumps might limit the pressure needed for circulating glycol within a system. This stalling might also limit the pumping pressure applied to the motor end of the pumps, and the output pressure of the pumped liquid materials.
Importantly, under certain conditions where the piston seals are blown during pumping, the piston seals may come into contact with the vent holes of the piston rod of these pumps. This in turn may cause the seals to be cut, damaged, or even shredded, as the piston rod reciprocates back and forth. Thus, piston seals may also be subject to abrasion and wear. As such, a need exists for a new and improved pump assembly to address the foregoing limitations.